Herceptin, the drug that attacks the HER2 cells, can cause heart failure. Only 1-2% is permanent, but doctors want to take precautions just in case. I was diagnosed with Mitral Valve Prolapse in 1988 after my last child was born, so my oncologist wanted to be extra careful. (Mitral Valve Prolapse is when one of the heart valves does not close properly between each beat. This may cause the valve to leak blood back into the heart after it has pumped it out. It is usually not very serious, but it is important to not get an infection above your heart. An infection will contaminate your blood and can cause it to leak back through the problem valve into the heart. Contaminated blood in your heart can be dangerous. This is why it is important to make sure that your teeth, for instance, are healthy.) Therefore, on Wednesday, September 6 I had an echocardiogram (ECG) to make sure my heart would be able to handle the Herceptin infusions. The cardiologist delivered some great news. My heart was p...